Lunar Reconnaissance Orbiter Camera

Debris over Impact Melt Pool

Debris avalanche covering an impact melt pond inside an unnamed crater floor. LROC NAC M182038126R. Image center is 4.135°S, 227.677°E, image width is 1083 meters. Downslope is toward upper right, north is to the top [NASA/GSFC/Arizona State University].

Today's Featured Image highlights the southwestern edge of the floor of an unnamed crater (6.8 km in diameter), located in the SW corner of the degraded Hertzsprung basin (540 km diameter). The rough hummocky surface (upper right) corresponds to an impact melt pond, which covers the floor of this crater. The debris avalanches originated from the crater wall and covered the melt pond surface in the lower left. These debris deposits follow the topographic gap along a fracture extending to the lower right from the center of this image, indicating that the fracture formed before the avalanche.

The NAC context view of the opening image (white frame), showing the unnamed crater floor. Image width is 3.0 km [NASA/GSFC/Arizona State University].

Impact melt ponds usually develop fractures and deformations of their surfaces (e.g. Melt and more melt, Channels And Fractures). The cause and timescale of such modification is unclear and still under discussion (e.g. Ashley et al., 2012) but is likely due to the crater subsurface re-adjusting as the impact melt cooled and hardened. The shape of impact craters slowly evolves over long periods of time. Thanks to the relatively slow erosional processes on the Moon relative to the Earth, we can observe a series of craters from young to very old with NAC images, helping scientists understand the process of crater formation and subsequent modification.  

The unnamed crater and surrounding area in LROC WAC monochrome mosaic (100 m/pix). Image center is 4.02°S, 227.72°E. The NAC footprint (blue box) and the location of opening image (yellow arrow) are indicated [NASA/GSFC/Arizona State University].

Explore the debris avalanche inside this young fresh crater in full NAC frame!

Related links:

More Impact Melt!

The View Inside of a Tilted Crater

Schiaparelli E

Channels And Fractures

Impact melt outside Wiener F

Rippled Pond

Melt and more melt

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